Vacuum pump



July 20, 1954 H. G. WARREN 2,684,195

VACUUM PUMP Filed Oct. 10, 1952 9 2 I 27 27 I 53 i 28 l 27 3o /6 t I 52 fli 34 9/ 36 liL iKfLU 37 4/ HORACE, a. WARREN INVENTOR. A4 .29 BY "P M A TTORNE Y3 NIT'ED STATES Patented July 20, 1954 VACUUM PUMP Horace G. Warren, Rochester; N1. Y assignor, by

Application October 10, 1952, Serial No. 314 182.

iENT OFFICE 5 Claims; 1.

This invention relates to vacuum pumps and is particularly concerned with high vacuum con.- densation pumps.

Various forms of the so-called; vertical con-. densation pumps are now being made for usev in a variety of high vacuum processes such as. vac.- uum distillation, tube evacuation, vacuum dehydration, vacuum coating and the like. The vertical condensation pumps consist essentially of a generally cylindrical pump body, including a boiler and a pump casing communicating with the boiler, and a jet assembly.- mounted in. the pump casing and generally concentric there.- with and comprising the combination of one or more vapor chimney elements arranged: tochannel pump fluid vapors from the boiler to the pumping zones and jet cap elements mounted on the chimney elements to form downwardly directed jet nozzles.

In operation, an inlet port near or at the top of the pump casing is connected to the system: to be. evacuated and an outlet port in a lower zone oi the pump casing is connected to a backing pump. Pumpfiuid is vaporized in the pumpboiler, the vapors ascend inside the chimneys and are. discharged downwardly from the jet nozzles and condensed on the pump casing, and the condensed: pumpfiuid is returned to the boiler.

For proper operation, it isnecessary that the various chmney and jet cap elements ofthejet assembly be properly aligned and spaced within the casing. Heretofore, thejet caps were usually welded or bolted to the chimneys which made it difiicult to fabricate the jet assemblies and, the pumps on an efiicient production basis and also made it diflicult to remove and clean the jet assembly or replace parts which might become damaged.

It is accordingly an object of this invention to provide a new and improve-d high vacuumcondensation pump.

It is a further object of the invention to: provide a high vacuum pump which is readily; as.- sembled. and disassembled.

It is also an object of the invention to provide a vacuum. pump wherein the, jet: assembly elements lend themselves to. mass production methods of fabrication and assembly.

Another object of the invention is to provide a, jet, assembly wherein the various chimney and jet: ca elements are. merely stacked upon each other in mating relation and including; means formaintaining the jet assembly in; rigid alignment in the pump; without. interfering to; any objectionable degree with the eas of} disassem bly Another object, of. the invention is to provide a vacuum pump. which is readily assembled even in very small sizes.

Gther objects will be apparent from the drawlugs and from: the: description and claims which follow.

These andother objects are attained by means of this; invention as described more fully hereinaiter with; particular reference to apreferred embodiment illustrated by.- the drawings.

Qt the. drawings:

Fig; l. is,- a; View in, elevation, partly broken aw y nd: in. sectio of. a. hi h: v cuum condensationpump. embodying, the invention; and

Fig, 2 is. a. section; taken: alon l 2-2 of Fig. 1;.

In a vacuum pumpembodying this invention, the pump. body comprises; a generally cylindrical pump casing ill of: metal or other suitable ma.- terial welded or otherwise secureditSlOWel end tov a. boiler H: for vaporizing pump. fluid. A jet assembly I 2, consisting of freely demountable mating chimney and: jet capv elements stacked together in; pumping relation as described more fully hereinafter, is disposed; in the piunp casing l'flconcentricwith the casing. Ehe bottom of the jet assembly it rests. on an annular ring, i=3: integral with: the pump. body,, and the demountable elements of; the jet. assembly l2. are held: to.- gether by a tie rodv M which. extends longitudinally. through the jet assembly l2. The lower end of tie rod I14. is adapted: toreleasably engage a spider l6 or similar element secured, to the pump body. Preferably; the lower end of tie rod 14; is bent tox forma hook t1; which. can be caught under spider is rigidly mounted. inside the pump. body. The upper end of the tie rod [4 projects above the, top of jet assembly (2, and a vertically displaceable pinning element I18 mounted on the upper end of'tie rod it pulls up.- wardlyon tie. rod M; and presses downwardly on the top of jet. assembly [2 whereby the various mating elements making: up the jet assembly are firmly held in position and the jet assembly is locked into the; pump.- body.

Referring particularly to. the preferred em.- bodiment illustrated in the drawings, the metal pump casing Hi hasa peripheral flange it at. its upper end for connecting thepump to the system to be evacuated. Elange has an annular groove 21 inits upper face, adapted to receive an O-ring gasket for ensuring a vacuum tight seal between the pump and the system; to be evacu; a-tcd. holes such: a shown at 22 being provided in flange 2%! for bolting the, flange to a suitable fitting (not shown) on the system to be evacuated. The mouth of the casing is thus serves as an inlet port 23 for the pump. An outlet port E i opens out of a lower zone of casing into a forepressure arm 25 which is welded or otherwise secured to casing it and which is adapted to be connected to a suitable backing pump. In the preferred embodiment, a series of baffles 2i, 2? are mounted within a vertical section 28 of forepressure arm 25 for condensing and collecting condensable volatiles entering the forepressure arm. The pump casing 69 and forepressure arm 25 are cooled by circulation of cooling fluid through a cooling coil 29 which desirably has the inlet end 36 extending along the forepressure arm 25 first and thence to the upper end of casing [0 adjacent inlet port 23 from which point it is coiled. around the casing in a downward spiral to the outlet end 3! adjacent the outlet port 24. This positioning of the cooling coil is preferred to give optimum cooling in the forepressure arm 25 and adjacent the inlet port 23 whereby backstreaming of pumping vapors into the system being evacuated and loss of pump fluid into the backing pump is minimized.

The lower end of easing it is welded to the top of boiler H around the mouth of the boiler. Boiler H has a sidewall 33 welded to a plate 34 which forms the bottom of the boiler, and has a conventional heater element 35 mounted against the lower face of plate 34. 36 opening out of sidewall 33 adjacent the bottom 3d of the boiler is internally threaded and closed by a threaded drain plug 3?. Heater element 35, which includes the usual resistance wires 38, 38 embedded in a ceramic plate 39 and connected to suitable binding posts as shown at 4!, is held in position against the lower face of plate 34 by means of an annular skirt d2 which fits inside the lower margin of sidewall 33 of the boiler below the heater and the skirt is secured to the boiler sidewall 33 by means of bolts 53, 43. m1- nular skirt t2 thus serves the dual function of a heater support and a base for the pump.

The upper portion of the boiler sidewall 33 is necked down and projects inwardly beyond the inner circumference of casing iii to form an annular ring it for supporting the jet assembly 12. The inner edge of ring it is bent upwardly in a peripheral lip 44 whereby ring l3 and the lower margin of casing It form an annular gutter in which the jet assembly rests. Spider i6 is welded to the peripheral lip 43 of the boiler and extends across the mouth of the boiler. The spider l6 A boiler drain is dimensioned so that the ends of its legs project part of the distance over the annular gutter and serve to center the lower end of jet assembly 22.

The jet assembly H! in the preferred embodiment illustrated in the drawings comprises mating chimney elements as. ti and 48 and jet cap elements .8 and 5c constructed to be arranged in stacked relation. The outer chimney element iii}, which is desirably machined from aluminum or similar material, rests-on annular ring 13 formed by the upper margin of boiler sidewall 33 and thus serves as the base for the jet assembly. Chimney as is centered by spider l6 and the lower end, which is in the annular gutter formed by ring 53 and casing Ii], is notched as shown at 52, 52 to permit flow of pump fluid around the lower end of chimney 45. The upper end of chimney element 46 is machined to form a shoulder 53 upon which jet cap 4% fits and the chimney wall is cut through to give spaced openings around the periphery of the chimney as shown at 5A for egress of pump fluid vapors under the flared skirt of jet cap 39. The top face of shoulder 53 is countersunk around the central opening of chimney 35 and serves as a beveled seat for the flared upper end of chimney element ti'l which hangs downwardly within the central bore of chimney 16 and forms an inner chimney spaced within and concentric with outer chimney 46. The inner chimney element 41 terminates immediately above spider Hi and the mouth of the boiler l0.

Jet cap element 49 which seats on shoulder 53 of outer chimney 46 also overlies the upper end of inner chimney element 47. Jet cap element 49 is drilled to provide an opening in alignment with and of the same diameter as the opening through inner chimney element ll. The upper chimney element 48 which is of the same internal diameter as the inner chimney element il and in effect forms an extension of element ii, seats in a countersunk seat on jet cap element t8 and projects upwardly to a region adjacent the inlet port 23. Chimney element =33 has a series of openings 55 through its wall adjacent its upper end, and umbrella jet cap element 58 seats on the upper end of chimney element 68 with the flaring skirt of cap 56 extending downwardly over the openings 50 to form a jet nozzle.

The various chimney and jet cap elements forming jet assembly G2 are maintained in the stacked relation described hereinabove by tie rod M which extends longitudinally down through the central bore of the jet assembly and which is adapted to have its lower end ll hooked under a leg of spider 16. The upper end of tie rod I l extends through an opening in umbrella jet cap 55 and projects upwardly substantially to the top of casing Hi. A spring seat 56, which is de sirably a plate clip or similar element which can be inserted on tie rod i4 and which resists displacement upwardly but which can be removed by sufiicient pressure, is mounted. on the upper portion of tie rod i4 above umbrella cap element 52% with a compressible spring 57 mounted on tie rod is and pinned between spring seat 56 and umbrella cap element 50 which forms the top of jet assembly l2.

When a removable spring seat is used, the hook I! at the lower end of tie rod i4 is desirably of such size that it cannot be withdrawn through the inner chimney element cl, although the spring seat 56 can be permanently mounted on tie rod it and hook ll be made small enough for withdrawal through the jet assembly.

In assembling the pump embodying the invention, the various chimney elements and jet cap elements are fitted together outside the pump to form the stacked assembly described hereinabove by dropping them into place over tie rod M. Spring 5'? is then slipped onto the upper end of tie rod Hi and spring seat 53 is forced downwardly into place abutting spring 5?. The entire jet assembly is then inserted into the pump body with the lower end of the jet assembly resting on the annular ring [3 and centered by spider 56. Tie rod M is then pressed downwardly to compress spring 5?, turned until hook I! is under a leg of spider I6, and released whereby the entire jet assembly is rigidly held together by the spring pressing down on the top of the assembly with the bottom of the assembly resting on annular support [3.

The pump is readily disassembled m rely by reversing the assembling procedure, and the entire jet assembly can be removed as a unit and disassembled for cleaning or replacement of indiacsvigioe vidual' elements if desired. No other means are necessary for securing the jet assembly elements together. The various elements can be mass produced and readily assembled and disassembled without tedious welding, riveting or bolting of the elements, The pump is readily fabricated and assembled regardless of size and thus lends itself to, production of small pumps forindividual exhausting units on multiple head exhausting apparatus. Accurate spacings are maintained rcgardless of the size of the pump.

In operating the pump embodying the invention, pump fluid is charged into the boiler, the pump is assembled as described, the inlet port connected to the system to be evacuated and the forepressure arm connected to a suitable; mehanical backing pump. Cooling water'is circulated through the cooling coil, and the heater element is energized. Pump fluid vapors formed in the boiler pass upwardly into the jet assembly, with part of the vapors ascending in the space between outer chimney element 46 and inner chimney element 4? and the remaining vapors passing upwardly through chimney elements 4'! and 48. The ascending vapors are discharged downwardly from the openings in the chimneys under the flaring jet caps and impinge on the cooled casing wall where they are condensed. The condensed fiuid flows downwardly into the annular gutter in which the lower end of the jet assembly rests forming a liquid seal around the lower end of the outer chimney element. The notched openings in the lower margin of the outer chimney element permits flow of pump fluid around the lower end of the outer chimney element, and as the pump continues to operate, the condensed fluid overflows the gutter and returns to the boiler for revaporization. Condensable volatiles entering the forepressure arm are condensed and collected by the baiiles positioned in the vertical section of the forepressure arm. Since the baffles are arranged at varying heights and so as to collect and hold pools of condensate, the baiiles not only ensure condensation of coin densable volatiles entering the forepressure arm but also act as fractionating alembics for segregating volatile components of the pump fluid which lower the pumping efiiciency.

The invention thus provides a pump which is readily produced and assembled in a wide range of sizes. The pump can be readily disassembled and parts of the jet assembly can be replaced with a minimum of eifort. Proper alignment of the various elements is ensured, and the jet assembly, although easily dismantled, is rigidly held in the pump during operation. The jet assembly cannot be blown out of the casing by sudden release of vacuum nor will it fall out when the pump is inverted.

Although the invention has been described in considerable detail with particular reference to a preferred embodiment of the invention, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as illustrated in the drawings and described hereinabove and as defined in the appended claims.

I claim:

I. A vacuum pump comprising a pump body including a boiler for vaporizing pump fluid and a pump casing communicating with said boiler and extending upwardly therefrom, the pump casing having an inlet and outlet, a jet assembly disposed in said pump casing and comprising freely demountable mating chimney and jet cap elements arranged in pumping relation, support means integral with said pumpbody and forminga base for said jet assembly, a rotatable tie rod extending longitudinally through said jet assem-. bly and having the upper end ofsaid tie rod projecting above the top ofsaid jet assembly, said tie rod including a spring seat rigidly mounted on said tie rod above said jet assembly, a compressiblespring mounted on said tierodand pinned between said spring seat and the top. of said jet assembly, and a crossmember extending transverse to the tie rod axis of rotation and rigidly mounted within said pumpbody adjacent the lower end of saidjet assembly, the lower end of-said tie rod extending atan angle to the upper portion of the tie rod so that the lower end of the tie rod engages and disengages under the cross member as the tie rod is rotated.

2. A vacuum pump comprising a generally cylindrical pump casing including an inlet port in an upper portion thereof and an outlet port in a lower portion thereof, a boiler secured to the lower end of said pump casing and opening into said casing, an annular gutter around the inner circumference of said pump casing adjacent the top of said boiler, a spider secured to said annular gutter and extending across the opening defined within said annular gutter, a jet assembly disposed within said casing and generally concentric therewith, said jet assembly comprising at least one chimney element and at least one mating jet cap element, said chimney element being disposed with its lower end resting in and supported by said annular gutter, said jet cap element nesting on said chimney element in stacked relation with said chimney element and being freely demountable therefrom, a tie rod extending longitudinally through said jet assembly and having the lower end of said tie rod bent to hook under said spider and having the upper end of said tie rod projecting above the top of said jet assembly, a spring seat mounted on said tie rod above said jet assembly, and a compressible spring encircling said tie rod and being pinned between said spring seat and the top of said jet assembly.

3. A vacuum pump comprising a generally cylindrical pump casing including an inlet port in an upper zone thereof and an outlet port in a lower zone thereof, a boiler secured to the lower end of said pump casing and opening into said casing, the upper marginal zone of said boiler being necked down into a peripheral lip forming an annular gutter around the inner circumference of said casing, a spider secured to said peripheral lip with at least one leg of said spider extending across the opening defined by said lip, a plurality of chimney elements and complementary jet cap elements, one of said chimney elements being disposed with its lower end resting in the gutter defined by said peripheral lip, said chimney elements and jet cap elements being nested together in stacked relation to form a demountable jet assembly disposed in pumping relation with said boiler and within said casing, a tie rod disposed centrally within said jet assembly and extending throughout substantially the length of said jet assembly, said tie rod being unsecured to the elements of said jet assembly, the lower end of said tie rod being bent to hook under a leg of said spider, the upper end of said tie rod projecting above the top of said jet assembly, a spring seat mounted on said tie rod above the top of said jet assembly, and a compressible spring disposed on said tie rod and pinned between said spring seat and the top of said jet assembly.

4. A vacuum pump comprising a pump body including a boiler for vaporizing pump fluid and a pump casing communicating with the boiler and extending therefrom, the pump casing having an inlet and outlet, a jet assembly disposed in the pump casing and comprising freely demountable mating chimney and jet cap elements arranged in pumping relation, a support means integral with the pump body and forming a base for the jet assembly, a rotatable tie rod extending longitudinally through the jet assembly and having one end of the tie rod projecting beyond the end of the jet assembly farthest removed from the boiler, pinning means mounted on the said end of the tie rod and pressing against the jet assembly to urge the jet assembly toward the boiler, and

a cross member extending transverse to the tie rod axis of rotation and rigidly mounted Within the pump body adjacent the end of the jet assembly nearest the boiler, the end of the tie rod nearest the boiler being provided with a projection extending at an angle to the rest of the tie rod so that the projection engages and disengages with the cross member as the tie rod is rotated.

5. The apparatus according to claim 4 wherein the pinning means is spring-loaded to urge the jet assembly toward the boiler.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,361,245 Stallman Oct. 24, 1944 2,432,226 Cox Dec. 9, 1947 

